Dempsey tweeted: "We met the green monster, looked her in the eye, and ... she blinked! We got it!"

Seattle is the hometown of global giant Starbucks.

A bankruptcy judge will have the final say on the bid on January 11.

If the deal is approved, Dempsey's company will pay $9.15m (£5.7m) and complete the purchase later this month.

"I'm thrilled that we won and I'm even more excited about saving Tully's Coffee and its hundreds of jobs," Dempsey said.

"Tully's is a great company with committed employees, and with its base in Seattle, one of the world's greatest cities, I'm confident we will be able to successfully build the brand and help grow the economy."

Tully's has 47 locations in several Western states and more than 500 employees.

It filed for Chapter 11 bankruptcy protection in October.

Dempsey, who has spent nine seasons on Grey's Anatomy - set in a fictional Seattle hospital - had said he wanted to rescue the chain.

"Seattle has been very good to me over my career, and I am honoured to have the privilege to own Tully's and work closely with the company's employees," he said in a statement.

Starbucks spokesman Zack Hutson confirmed his company participated in the auction and "is currently in a back-up position" for some of Tully's assets.